1//===-- lib/fixdfsi.c - Double-precision -> integer conversion ----*- C -*-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is dual licensed under the MIT and the University of Illinois Open
6// Source Licenses. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file implements double-precision to integer conversion for the
11// compiler-rt library.  No range checking is performed; the behavior of this
12// conversion is undefined for out of range values in the C standard.
13//
14//===----------------------------------------------------------------------===//
15
16#define DOUBLE_PRECISION
17#include "fp_lib.h"
18
19#include "int_lib.h"
20
21ARM_EABI_FNALIAS(d2iz, fixdfsi)
22
23COMPILER_RT_ABI int
24__fixdfsi(fp_t a) {
25
26    // Break a into sign, exponent, significand
27    const rep_t aRep = toRep(a);
28    const rep_t aAbs = aRep & absMask;
29    const int sign = aRep & signBit ? -1 : 1;
30    const int exponent = (aAbs >> significandBits) - exponentBias;
31    const rep_t significand = (aAbs & significandMask) | implicitBit;
32
33    // If 0 < exponent < significandBits, right shift to get the result.
34    if ((unsigned int)exponent < significandBits) {
35        return sign * (significand >> (significandBits - exponent));
36    }
37
38    // If exponent is negative, the result is zero.
39    else if (exponent < 0) {
40        return 0;
41    }
42
43    // If significandBits < exponent, left shift to get the result.  This shift
44    // may end up being larger than the type width, which incurs undefined
45    // behavior, but the conversion itself is undefined in that case, so
46    // whatever the compiler decides to do is fine.
47    else {
48        return sign * (significand << (exponent - significandBits));
49    }
50}
51